Just a thought for you.
I have just purchased 2nd hand, a 1993 Swift Piroette caravan here in NZ.
It has had a leak, induced because it had been driven under a low roof which stressed the out edge, on the road side and yes it had leaked. Previous owner applied a vinyl tape of suitable colour along outer RH top edge of roof. Dry, no more water leak and it looks fine.
David N
February 2011